U.S. patent number 6,478,100 [Application Number 09/369,086] was granted by the patent office on 2002-11-12 for supercharged hybrid electric vehicle.
This patent grant is currently assigned to Bae Systems Controls, inc.. Invention is credited to Timothy Michael Grewe.
United States Patent |
6,478,100 |
Grewe |
November 12, 2002 |
Supercharged hybrid electric vehicle
Abstract
A hybrid electric vehicle (10) includes an internal combustion
engine (12) which drives a generator (20) to produce electrical
energy for a traction motor (44) of the vehicle. The generator (20)
is provided with a cooling air intake port (20i). A air mover or
compressor (30) is driven from the engine (12) or from an auxiliary
motor (84), to produce air under positive pressure. The air from
the air mover (30) is coupled by air paths (60, 62, 64) to the
cooling air input port (20i) of the generator (20) and to the
combustion air aspiration or input port (16) of the engine (12). If
the air mover serves the purpose of cooling the generator (20) and,
if a non-positive-displacement pump, also provides an effect
similar to turbocharging, and if a positive-displacement type,
supercharges the engine (12).
Inventors: |
Grewe; Timothy Michael
(Endicott, NY) |
Assignee: |
Bae Systems Controls, inc.
(Johnson City, NY)
|
Family
ID: |
23454055 |
Appl.
No.: |
09/369,086 |
Filed: |
August 5, 1999 |
Current U.S.
Class: |
180/65.245;
180/68.2; 180/68.3; 903/951; 903/905 |
Current CPC
Class: |
B60K
6/46 (20130101); F02B 33/40 (20130101); B60K
6/24 (20130101); B60W 10/30 (20130101); F02B
63/04 (20130101); B60K 6/40 (20130101); F02B
33/36 (20130101); Y10S 903/905 (20130101); Y02T
10/6295 (20130101); Y02T 10/6217 (20130101); Y02T
10/62 (20130101); Y10S 903/951 (20130101) |
Current International
Class: |
B60K
6/00 (20060101); B60K 6/04 (20060101); F02B
33/36 (20060101); F02B 33/40 (20060101); F02B
63/04 (20060101); F02B 63/00 (20060101); F02B
33/00 (20060101); B60K 006/02 () |
Field of
Search: |
;180/65.2,65.3,65.4,68.1,68.2,68.3 ;123/26,198R ;310/63 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mar; Michael
Attorney, Agent or Firm: Meise; William H. Krauss; Geoffrey
H.
Claims
What is claimed is:
1. A hybrid electric vehicle comprising: an internal combustion
engine which receives fuel, mixes the fuel with air from an air
intake port to thereby form a fuel-air mixture, and combusts the
fuel-air mixture to rotate a drive shaft; a traction motor for
driving said vehicle; an electrical generator mechanically coupled
to said drive shaft, for being driven by rotation thereof, for
generating electrical power for use by said traction motor, said
generator including a cooling air input port; an air mover
pneumatically coupled to said air intake port and said cooling air
input port, for creating a positive air pressure, and for coupling
said positive air pressure to said air intake port and to said
cooling air input port, said air mover being ultimately driven by
said engine.
2. A vehicle according to claim 1, wherein said internal combustion
engine is a diesel engine.
3. A vehicle according to claim 1, further comprising mechanical
coupling means coupled to said drive shaft of said engine and to
said air mover, so that said air mover is driven in response to
mechanical rotation of said drive shaft.
4. A vehicle according to claim 3, wherein said mechanical coupling
means comprises a shaft of said electrical generator.
5. A vehicle according to claim 1, further comprising electrical
coupling means coupled to said air mover and ultimately coupled to
said electrical generator.
6. A vehicle according to claim 5, wherein said electrical coupling
means comprises a battery and an auxiliary electric motor.
7. A method for operating a hybrid electric vehicle, said method
comprising the steps of: rotating a drive shaft of an internal
combustion engine by combusting fuel with air from an air intake
port; rotating an electrical generator in response to rotation of
said drive shaft, for thereby generating electrical power; from
time to time, operating an electrical traction motor using said
electrical power, for thereby driving said vehicle; driving an air
mover for compressing air; and routing compressed air from said air
mover to a cooling air input port of said generator and to said air
intake port of said engine.
8. A method according to claim 7, wherein said step of driving said
air mover includes the step of: coupling mechanical rotation of
said drive shaft to a drive shaft of said air mover.
9. A method according to claim 7, wherein said step of driving said
air mover includes the step of: applying electrical energy to an
auxiliary electrical motor mechanically coupled to said air mover.
Description
FIELD OF THE INVENTION
This invention relates to hybrid electric vehicles, and more
particularly to such vehicles using an internal combustion engine
which receives combustion air under pressure.
BACKGROUND OF THE INVENTION
Enhancement of the operation of internal combustion engines by the
use of superchargers has been known for almost a century. In
general, a supercharger is an air pump which is driven by the
engine, and which compresses the air provided to the air intake
port of the engine. The air pump of a supercharger is often
described as being "positive-displacement," to thereby indicate
that a fixed volume of air is move during each rotation of the
compressor shaft. Compression of the air provided to the intake
manifold allows a greater mass of air to be forced into each
cylinder during the intake portion of the operating cycle, which in
turn allows combustion of a greater mass of fuel during each cycle
of operation. This improves the "volumetric efficiency" or the
amount of power which can be produced by each increment of
displaced volume. More power can be produced by an engine operating
with a supercharger than by a corresponding engine lacking a
supercharger.
It was discovered that supercharging an engine did indeed increase
the output power or torque, but it also increased the stresses on
engine parts, which tended to contribute to a lesser reliability.
The power gains achieved by a supercharger tended to be less than
expected, because of the shaft power consumed by the air compressor
itself. A concomitant of the use of a supercharger to improve the
volumetric efficiency an increase in the fuel consumption per
displaced volume, because the ratio of fuel to air remains
relatively constant for proper combustion. In general, it was found
to be more practical to achieve increased power by a conventionally
aspirated engine of larger displacement than by a supercharged
engine.
Turbocharging was devised as a method for achieving some of the
gains of supercharging, without attendant disadvantages. A
turbocharger is an air compressor, generally centrifugal, which is
driven by a turbine associated with the exhaust of the internal
combustion engine. The exhaust gases drive the turbine, which spins
the centrifugal compressor, and the resulting compressed air is
provided to the air intake port of the engine to provide improved
volumetric efficiency.
As with superchargers, turbochargers were found to be less than
perfect. Early turbocharged vehicles suffered from carbonization of
lubricating oil in the turbine due to the heat of the exhaust gases
driving the turbine, and this effect was found to be most egregious
when the engine was turned off, as the oil "baked" in place, as oil
flow stopped concurrently with turning off of the engine. It had
initially been anticipated that the energy for driving the
turbocharger was "free" in that the drive energy would otherwise be
wasted; the effect of the presence of the turbine in the exhaust
system of the engine tended to increase the back pressure, which
tended to offset the improvement in volumetric efficiency provided
by the positive pressure at the air intake port. Another
disadvantage of the turbocharger is that of "lag," which refers to
reduction of the boost air pressure, during acceleration, relative
to what might be expected at a corresponding static engine speed.
In other words, the turbine speed lagged the engine speed, due to
inertia or possibly other factors. Consequently, the boost air
pressure during acceleration, when extra power or torque is needed,
was small, while the boost air pressure during cruise was large,
but generally unnecessary. These disadvantages resulted in little
use of turbochargers in gasoline-powered automobiles.
Since the early 1970s, there has been an emphasis on vehicle fuel
mileage. The Government has promulgated fleet mileage requirements
in an attempt to reduce overall fuel consumption. In response to
the perceived need for improved mileage, automobiles have been made
lighter, and engine displacements have been reduced. The reduction
in shaft power per operating cycle occasioned by the reduced
displacements has been partially overcome by increasing the engine
operating speeds. These changes, coupled with modern electronic
control systems, has been effective in maintaining perceived
automobile performance, while improving fuel mileage.
In an effort to further improve mileage, automotive manufacturers
have been experimenting with nonstandard propulsion systems. One
proposed vehicle drive system is powered by a tank of compressed
air, but this arrangement lacks range, and is not readily
"refueled" as its compressed-air tanks require pressures which may
exceed those readily available at gas stations. Battery-powered
electrically-driven vehicles are available, but are widely
recognized as having insufficient range for ordinary use.
Improvements in battery technology may one day make such
battery-operated vehicles practical. However, the need to recharge
the batteries with substantial amounts of energy means that
technological and infrastructure changes may be required to provide
fast charging at convenient "electric" recharge stations.
A fuel-consuming hybrid electric vehicle has come to be considered
more practical than a pure-electric vehicle because of its ability
to use conventional liquid-fuel infrastructure, because of its
relatively great range, attributable to the relatively high energy
density of liquid fuels. The environmental objections to such
vehicles appear to be decreasing, as the effects of operation of
coal-fired and other electrical generating plants on the
environment, attributable to the need to produce the energy to
recharge electric vehicles, becomes widely known.
Improved vehicles are desired.
SUMMARY OF THE INVENTION
A hybrid electric vehicle according to an aspect of the invention
includes an internal combustion engine which receives fuel, mixes
the fuel with air from an air intake port to thereby form a
fuel-air mixture, and combusts the fuel-air mixture to rotate a
drive shaft. The vehicle also includes an electrically operated
traction motor for driving the vehicle. An electrical generator is
mechanically coupled to the drive shaft of the engine, for being
driven by its rotation. Rotation of the generator, in turn,
generates electrical power for use by the traction motor. The
traction motor may receive the electrical power directly from the
generator, but a preferred arrangement converts alternating current
from the generator into direct voltage, which is stored in a
traction battery, used by the traction motor, or both. The
generator includes a cooling air input port, to which pressurized
air is provided for cooling the generator. An air mover is
pneumatically coupled to air intake port of the engine and to the
cooling air input port of the generator, for creating a positive
air pressure, and for coupling the positive air pressure to the air
intake port and to the cooling air input port. In a preferred
embodiment of the invention, the air mover is mechanically driven
from the generator shaft, or ultimately from the drive shaft of the
engine by way of any intermediary mechanical arrangement. In
another embodiment, the air mover is driven by an auxiliary
electrical motor, which is preferably powered from a battery which
is recharged by the generator. In one embodiment, the internal
combustion engine is a diesel engine.
A method, according to another aspect of the invention, is for
operating a hybrid electric vehicle. The method includes the step
of rotating a drive shaft of an internal combustion engine by
combusting fuel with air from an air intake port. The shaft of an
electrical generator is rotated in response to rotation of the
drive shaft, for thereby generating electrical power. The traction
motor is operated from time to time using electrical power, to
drive, or to aid in driving, the vehicle. An air mover or
compressor is operated in order to produce compressed air. The
compressed air is routed from the air mover to a cooling air input
port of the generator and to the air intake port of the engine.
According to a preferred mode of the method of the invention, the
step of driving the air mover includes the step of coupling
mechanical rotation of the drive shaft to a drive shaft of the air
mover. This step may include the step of driving an intermediary
device, which is preferably the generator shaft. In an alternative
mode of the method, the step of driving the air mover includes the
step of applying electrical energy to an auxiliary electrical motor
mechanically coupled to the air mover. This auxiliary electrical
motor may be driven from a battery which is recharged by the
generator.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a simplified diagram illustrating a vehicle or system
according to the invention;
FIG. 2 is a simplified illustration of a portion of the system of
FIG. 1, which includes a speed-adjusting gearbox;
FIG. 3 is a simplified illustration of a mechanical coupling of the
shaft of the air mover or air compressor to the drive shaft of the
motor in parallel with the connection of the shaft of the generator
to the drive shaft of the engine; and
FIG. 4 is a simplified illustration of an arrangement according to
an aspect of the invention in which the air mover is driven by an
auxiliary electrical motor.
DESCRIPTION OF THE INVENTION
Series hybrid electric vehicles are described in U.S. Pat. No.
5,828,201, issued Oct. 27, 1998 in the name of Hoffman et al. and
U.S. Pat. No. 5,869,950, issued Feb. 9, 1999 in the name of Hoffman
et al.; allowed patent applications Ser. No. 09/044,669, filed Mar.
20, 1998 in the name of Lyons et al., U.S. Ser. No. 09/044,671
filed Mar. 20, 1998 in the name of Lyons et al., and U.S. Pat. No.
09/039,895 filed Mar. 16, 1998 in the name of Gataric et al.; and
in patent applications Ser. No. 09/192,645, filed Nov. 16, 1998 in
the name of Jones et al., U.S. Ser. No. 09/044,670, filed Mar. 20,
1998 in the name of Lyons et al., U.S. Ser. No. 09/044,676, filed
Mar. 20, 1998 in the name of Lyons et al., U.S. Ser. No.
09/039,896, filed Mar. 16, 1998 in the name of Lyons, U.S. Ser. No.
09/177,011, filed Oct. 22, 1998 in the name of Chady et al., U.S.
Ser. No. 09/080,148, filed May 18, 1998 in the name of Lyons et
al., and U.S. Ser. No. 09/266,646, filed Mar. 16, 1999 in the name
of Gataric. Series-type hybrid electric buses experimenting or
using some of this technology are currently in operation as, for
example, transit buses in New York. It appears that they are well
received.
FIG. 1 illustrates a hybrid electric vehicle as generally described
in the abovementioned patents documents. In the system of vehicle
10 of FIG. 1, an internal combustion engine 12 is associated with a
fuel tank 14. Engine 12 aspires air from an input port 16, and uses
the air to combust fuel in the cylinders, in known fashion. The
energy produced by the combustion is converted into rotational
motion of a drive shaft 18. An alternating-current generator 20 has
one end of its shaft 22 connected to shaft 18 at a junction 24, so
that the shaft 22 of the generator 20 rotates with rotation of
drive shaft 18. A positive-displacement air mover or air compressor
30, has its shaft 32 coupled at a joint 33 to shaft 22 of the
generator 20. Thus, there is a direct mechanical connection between
engine 12 drive shaft 18 and air compressor 30 shaft 32.
The electric power produced by generator 20 of FIG. 1 is coupled by
way of a path illustrated as 38 to a controllable power-handling
inverter/converter (inverter) 40. Inverter 40 is also connected to
a traction battery illustrated by a conventional battery symbol 42,
and to a traction motor/generator (motor) 44. Traction motor 44 is
mechanically coupled, by way of differential gearing 46, if
desired, to vehicle drive wheels 48a and 48b. The user displays and
controls are illustrated as a block 50, The user displays are
coupled to a command processor 52, which performs most of the
control functions for the vehicle propulsion system, as described
in more detail in the abovementioned patents documents.
According to an aspect of the invention, the compressed or
positive-pressure air from air mover or air compressor 30 of FIG. 1
is routed as cooling air to generator 20 and to air input port 16
of engine 12. As illustrated in FIG. 1, the air is routed from an
air output port 30o, by way of a duct or tube 60 to a tee junction
62. One arm of tee junction 62 connects by way of a further duct or
tube 64 to air input port 16 of engine 12, and the other arm of tee
junction 62 connects to a cooling air input port 20i of generator
20. In operation, the air mover or air pump 30 operates at the same
number of rotations per minute (RPM) as the engine, so cannot be
subject to lag. Consequently, boost air pressure can be made
available at the air input port 16 of the engine, even at low RPM,
by appropriate sizing or dimensioning of the pump in relation to
the engine displacement.
The arrangement of FIG. 1 allows use of an air pump for dual use,
more specifically for supercharging the engine as well as for
cooling the generator. The saving in weight attributable to not
having separate air movers is important, considering that fuel
savings are very desirable in modern vehicles, and it also
contributes to reliability.
FIG. 2 is a simplified illustration of a portion of a system in
accordance with an aspect of the invention, which is similar to the
system of FIG. 1, but which includes a speed-adjusting gearbox. In
FIG. 2, elements corresponding to those of FIG. 1 are designated by
like reference numerals. In FIG. 2, a gearbox 70 is interposed
between engine shaft 18 and generator shaft 22, for increasing the
rotational speed of the generator 20 and compressor 30 by
comparison with the rotational speed of engine shaft 18. As an
alternative, the gearbox 70 could be placed in the position
illustrated by dash lines in FIG. 2, joining the shafts of the
generator and the air compressor or air mover 30, to thereby
increase the rotational speed of only the air compressor.
The arrangement of FIG. 3 illustrates a mechanical coupling of the
shaft of the air mover or air compressor to the drive shaft of the
motor in parallel with the connection of the shaft of the generator
to the drive shaft of the engine. More particularly, in FIG. 3, a
pulley 72 is connected to shafts 18 and 22, and is connected by a
belt 74 to a further pulley 76, which drives shaft 32 of the air
mover or compressor 30.
In FIG. 4, the engine 12 shaft 18 drives shaft 22 of generator 20,
but the air mover or compressor 30 shaft 32 is driven by an
auxiliary electric motor 84. The auxiliary motor 84 is powered by
electrical power taken from traction battery 42 by way of a path 82
and an auxiliary controller 80. It should be understood that
auxiliary controller 80 is illustrated as separate only for
explanation, and it may actually be integrated partially into power
controller 40 and partially into command controller 52. Auxiliary
controller 80 determines the amount of supercharging boost pressure
depending upon conditions; when the engine is off, no boost should
be supplied, and when the engine is on, the boost could be
constant, or follow some law such as increasing the pressure boost
in the presence of an increase in the load or drain from the
generator 20.
Other embodiments of the invention will be apparent to those
skilled in the art. For example, while the hybrid electric vehicle
has been described as a "series" type arrangement in which the
internal combustion engine drives only the generator, and the only
mechanical traction power comes from the electric motor, the
invention may also be used in a "parallel" system in which both the
traction motor and the internal combustion engine mechanically
drive the vehicle's wheels. While a positive-displacement air mover
has been described, the air mover could a centrifugal or other
non-positive-displacement type, and could be geared to the engine
(or generator) shaft with a gear ratio selected to provide a
different range of RPM than for a conventional turbocharger; in
such an arrangement, the problem of heating of the air pump by the
high-temperature exhaust gases is overcome. While the illustrations
show long air paths, such as paths 60 and 62, extending between the
air mover and the two air users, the engine air input port 16 and
the cooling air input port 20i of generator 20, those skilled in
the art know that the presence of such paths tends to impede the
flow of air, and that air flow is enhanced if the paths are kept as
short as possible, and have the largest possible transverse
dimensions. Those skilled in the art also know that compressing air
in a compressor such as 30 of the FIGURES tends to heat the air,
and that warm air provides less volumetric efficiency than cold
air; they also know that may be desirable to cool the compressed
air with an intercooler before applying it to the air input or
aspiration port 16 of the engine 12.
Thus, the invention lies, in part, in a hybrid electric vehicle
(10) which includes an internal combustion engine (12). The
internal combustion engine receives fuel (from tank 14), mixes the
fuel with air from an air intake port (16) to thereby form a
fuel-air mixture, and combusts the fuel-air mixture to rotate a
drive shaft (18). The vehicle (10) also includes an electrically
operated traction motor (44) for driving the vehicle (10). An
electrical generator (20) is mechanically coupled (shaft 22 at
joint 33) to the drive shaft (18) of the engine (12), for being
driven by its rotation. Rotation of the generator (20), in turn,
generates electrical power for use by the traction motor (44). The
traction motor (44) may receive the electrical power directly from
the generator (20), but a preferred arrangement converts (by
controller 52 and power control 40) alternating current from the
generator (20) into direct voltage, which is stored in a traction
battery (42), used by the traction motor (44), or both. The
generator (20) includes a cooling air input port (20i), to which
pressurized air is provided for cooling the generator (20). An air
mover (30) is pneumatically coupled to air intake port (16) of the
engine (12) and to the cooling air input port (20i) of the
generator (20), for creating a positive air pressure, and for
coupling the positive air pressure to the air intake port (16) and
to the cooling air input port (20i). In a preferred embodiment of
the invention, the air mover (30) is mechanically driven (by way of
shaft 22, or by way of pulleys 72 and 76, and belt 74) from the
generator (20) shaft, or ultimately from the drive shaft (18) of
the engine (12) by way of any intermediary mechanical arrangement.
In another embodiment, the air mover (30) is driven by an auxiliary
electrical motor (84), which is preferably powered from a battery
(42) which is recharged by the generator (20) (20). In one
embodiment, the internal combustion engine (12) is a diesel engine
(12).
A method, according to another aspect of the invention, is for
operating a hybrid electric vehicle (10). The method includes the
step of rotating a drive shaft (18) of an internal combustion
engine (12) by combusting fuel with air from an air intake port
(16). The shaft (22) of an electrical generator (20) is rotated in
response to rotation of the drive shaft (18), for thereby
generating electrical power. The traction motor (44) is operated
from time to time using electrical power, to drive, or to aid in
driving, the vehicle (10). An air mover (30) or compressor is
operated in order to produce compressed air. The compressed air is
routed from the air mover (30) to a cooling air input port (20i) of
the generator (20) and to the air intake port (16) of the engine
(12). According to a preferred mode of the method of the invention,
the step of driving the air mover (30) includes the step of
coupling mechanical rotation of the drive shaft (18) to a drive
shaft of the air mover (30). This step may include the step of
driving an intermediary device, which is preferably the generator
(20) shaft. In an alternative mode of the method, the step of
driving the air mover (30) includes the step of applying electrical
energy to an auxiliary electrical motor (84) mechanically coupled
to the air mover (30). This auxiliary electrical motor (84) may be
driven from a battery which is recharged by the generator (20).
* * * * *